Apparatus for mixing farinaceous or pulverous materials by means of compressed air



2,205,525 APPARATUS FOR MIXING FARINACEOUS on PULVEROUS P. GOEBELS Julie 25, 1940.

MATERIALS BY MEANS OF COMPRESSED AIR Filed Feb. 9, 1938 2 Sheets-Sheet 1' June 25, 1940. R'GOEBELS 2,205,525

APPARATUS FOR MIXING FARINACEOUS on PULVEROUS IATERIALS BY MEANS OF COMPRESSED AIR v Filod Feb. 9, 1938 2 Sheets-Sheet 2 Patented June 25, 1940 UNITED STATES PATENT OFFICE I COMPRESSED AIR Paul Goebels, deceased, late of Dess'au, Germany, by Lina Goebels, executrix, Dessau, Germany Application February 9, 1938, Serial No. 189,698

In Germany February 9, 1937 1 9 Claims.

This invention relates to the mixing of finely divided or pulverulent materials; and has for its object the provision of apparatus which is relatively simple and inexpensive to construct and operate, which is not adversely affected by the extremely high pressures developed by the movement of large quantities of material, and which functions efficiently to intimately mix the materialand to prevent stratification thereof in layers of different density, physical condition, and chemical nature.

It has been heretofore proposed to mix finely divided materials by circulating the same within a mixing chamber, air or other gaseous medium under pressure being employed to maintain the material in circulation, the use of mechanical agitating devices being thus avoided. It is with this general class of mixing devices that the present invention is concerned.

It is essential to the complete and eflicient mixing of materials by devices of this character that material be withdrawn from different strata and brought into intimate contact. appreciated that if the material is circulated by continuously transferring the'same between the lower and the upper portions only of the chamber, the material at any given level may be thoroughly mixed, but there will be no effective mixing of materials in different levels, and Stratification of the material will inevitably persist.

It is therefore proposed as part of the present invention to continuously and simultaneously withdraw material from different levels of a mixing chamber and to commingle the same. The commingling of the material may be effected by the return of the material so withdrawn to a common level, preferably to the upper end of the chamber. A feature of the invention is the location exteriorly of the chamber of conduits for withdrawing material from different strata, the damaging of the conduits by excessive pressures developed within the chamber as the result of the movement therein of large quantities of material being thereby avoided. Again, it is proposed that these exteriorly located conduits shall be of ample transverse sectional area to reduce the possibility of the packing of material therein under the heavy pressures existing within the chamber. If stoppage should occur under unusual conditions, it may be immediately observed through transparent wall sections of the conduits and the condition promptly and readily corrected. Smaller conduits or pipes are preferably utilized to convey the material upwardly after it has been withdrawn from the chamber through the large Thus it will be.

conduits, the velocity of a given volume of propelling gas being greater in the smaller pipes, so that the upward aspiration of the material is facilitated.

Thus it is a more specific object of the invention to provide a mixing chamber for pulverulent material, for example cement raw material, having a plurality of relatively large conduits communicating at different levels with the interior of the chamber, such conduits being so disposed that the material flows from the chamber into the conduits under the pressure existing within the chamber, and flows within the conduits by gravity, each conduit having associated therewith, and preferably extending therein, a smaller pipe through which the material is returned from the conduit to the upper portion of the chamber by the action of gas under pressure.

A still further object of the invention is the provision, in a chamber of the type employin conduits for moving the material from one portion of the chamber to another, of means for establishing a fluid condition of the material with-' in the chamber by suitable aeration so as to eliminate the possibility of packing of the material within the conduits and in the chamber itself. This aerating means may comprise devices for introducing air or other gaseous medium into the chamber and/or into the conduits in a state of extremely fine division, for example by passing the gaseous medium'through porous material.

' Further objects and features of the invention will be apparent from the following description taken in connection with the accompanying drawings, in which Figure 1 is a vertical sectional view of a mixing chamber having associated therewith apparatus constructed in accordance with the principles of the invention;

Figure 2 is a horigontal sectional view on the line C--D of Figure 1;

Figure 3 is a horizontal sectional view on line EF of Figure 1; and

Figure 4 is a horizontal sectional view on the line G-H of Figure 1.

To facilitate an understanding of the invention, reference is made to the specific embodment thereof illustrated in the drawings and 'specific language is employed in describing the same. It will nevertheless be understood that various alterations and modifications of the structure shown and described herein are contemplated such as would occur to one skilled in the art.

In the apparatus illustrated, the mixing chamthe ber is indicated at I and is shown as generally cylindrical in shape and as provided with an inlet 2 at the upper end and an outlet 3 at the lower-end. A plurality of downwardly directed conduits 4 are disposed at intervals about the peripheral wall defining the' chamber I, these conduits communicating at their upper ends with the interior of the chamber through openings 5, 6, and 1 formed inthe chamber wall and disposed at different horizontal levels. It will be observed that the conduits 4 and the several openings therefrom into the interior of the chamber I are of ample size in order that possibility of stoppage by clogging of material therein may be reduced to a minimum.

Extending to a point "adjacent the lower end of 'each conduit, and preferably disposed longitudinally of and within each conduit, is a smaller conduit or pipe 8, the pipes 8 communicating at their upper ends with the interior of chamber I at'substantially the same horizontal level. lower ends of the pipes 8 may be flared as indicated at 9 to facilitate the aspiration of the pulverulent material upwardly therein,, nozzles I2 through which is directed a gaseous medium such as air under pressure being disposed beneath the lower ends of the pipes 8 and being directed to-v ward the flared portions 9 thereof.

In order that free circulation and intimate mixture of the materials in the chamber I and in the conduits 4 may be assured, it is preferable to establish a substantially fluid condition of the material either in the chamber I, the conduits 4, or in both, by suffusing the material with a gaseous medium in an extremely finely divided state. Thus it will be observed that a wall I is positioned in the lower end of the chamber I, this wall serving as a support for the material in the chamber. The wall I I) is spaced from the bottom of the chamber and air or other gaseous medium. under pressure is introduced into this space through a plurality of ducts I3. The wall I0 is formed of a gas-pervious substance, for example filter stone, porous brick, porous caoutchouc, or any other matr *ial having a multiplicity of extremely fine perforations therein. The gaseous medium passes through the wall Iii into the chamber I in a state of extremely fine division, whereby the material within the chamber is not only very noticeably expanded, but attains a mobile, fluid, or suspended state, and is thus capable of flowing readily through the openings 5,

G, and I and downwardly through the conduits 4.

Similarly, a false bottom I of a porous substance may be disposed in the lower end of each conduit 4, gas under pressure being introduced through the duct I8 beneath these bottoms to suifuse the material in the conduits with finely divided gas to maintain the material in a condition approaching fluidity and to facilitate movement of the material within the pipes 8. The'nozzles I2 and the ducts I3 and I8 may be supplied with a gaseous medium under pressure from a common supply pipe I1, flow through the individual ducts and nozzles being controlled by suitable valves as shown.

From the foregoing description the mode of operation of the structure shown in the drawings will be apparent, The chamber I is supplied with pulverulent material of similar or different character and physical condition, the material being withdrawn after thorough mixing through the outlet 3 at the bottom of the chamber. If desired, the process may be carried out continuously by constantly and simultaneously supply- The - for.

ing material to the chamber and discharging the same from the lower end thereof, but it is ordinarily preferable, in order to ensure complete mixing, to partially or completely fill the chamber, operate the mixing devices for a suflicient period of time to effect complete commingling of the material, and thereafter discharge the mixed material from the chamber.

Under the pressure which exists within the chamber 1 by reason of the weight of the material therein, the latter flows outwardly through the several openings 5, 8, and 1, downwardly In the conduits 4, and is aspirated upwardly through the pipes 8, being returned to a common level at the upper end of the chamber, at which point the materials from. several different levels within the chamber are intimately commingled. There may be effected, of course, commingling of these materials in a separate or auxiliary chamber before returning the same to the main mixing chamber, for example as illustrated more particularly in Figure 5 of the copending application Serial No, 67,128, filed March 4, 1936, and this is contemplated as a modification of the apparatus illustrated herein.

The infiltration or suffusion of gas into the chamber I and into the lower ends of the conduits 4 not only facilitates circulation of the material and prevents clogging of the conduits 4 and pipes 8, but serves in itself to effectively mix the material within certain limits.

While in the preferred form of the invention illustrated in the drawings, ample precautions are taken to prevent clogging of the conduits 4, in other forms of apparatus constructed within the scope of the invention and under certain conditions it is possible that difficulty may be encountered, particularly on the initiation of operation of the apparatus when the material is relatively densely packed within the chamber I. In order that such clogging of the conduits 4 may be readily observed, it is preferred to provide in the wall of each such conduit a window or transparent section I8 for periodic inspection. It will be appreciated that owing to the fact that the conduits are disposed outside of the mixing chamber I, removal of the conduits in order to correct any defective condition may be readily effected.

The exterior location of the conduits 4 has the further advantage, previously referred to, of removing these conduits and the associated pipes 8 from direct contact with the bulk of the material within the chamber I, it having been found difficult to prevent the bending and breaking of conduits and pipes having a generally similar function but supported within the chamber, the movement of large masses of material within the chamber exerting considerable pressure on the same. Again, by the arrangement of theconduits and pipes illustrated herein, the material is free to move downwardly within the chamber l without the obstruction which would otherwise be offered by the apparatus required to circulate the material and by the supporting means there- It is of course not always essential to the effective mixing of powdered materials that all of the features illustrated herein be employed,

and the invention contemplates the use of various subcombinations of elements-such as are'included within the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be' secured by Letters Patent is:

1. In apparatus for mixing pulverulent or finely chamber, said means including at least one pipe divided materials, the combination with a mixing chamber receiving the material to be mixed, of a plurality of conduits disposed exteriorly of said chamber and communicating with the interior of said chamber at different vertical lev-' els, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom, and means associated with said conduits for returning the withdrawn material to said chamber at a point above the highest level of withdrawal. p

' 2, In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed,

duits for returning the withdrawn material to said chamber at a point above the highest level of withdrawal, the walls of said exterior conduits having transparent sections therein the externalpositioning of said conduits and the provision of said transparcntsections cooperating to provide means, whereby the movement of ma terial in the conduits maybe observed and whereby any abnormal functioning of the device may be readily corrected. p

3. In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to bemixed,

of a plurality of conduits disposed exteriorly of,

said chamber and communicating with the interior of said chamber at difierent vertical lev-' els, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom, means associated with said conduits for returning the withdrawn material to said of smaller transverse sectional area than said conduits communicating with each of the latter and with said chamber, and means. for causing a gaseous medium to flow within said pipes away from said conduits.

4. In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed,

of a plurality of conduits disposed exteriorly of said chamber and communicating with the interior of said chamber at different vertical levels, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom, means associated with said conduits for returning the withdrawn material to said chamber, said means including at least one pipe of smaller transverse sectional area than said conduits communicating with each of the latter and with said chamber, and means for causing a gaseous medium to flow within said pipes away 'from said conduits, each of said pipes extending partially within and longitudinally of the associated conduit.

5. In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed, of a plurality of downwardly directed conduits disposed 'exteriorly of said chamber and.communicating with the interior of said chamber at diiferent vertical levels, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom and discharged downwardly therein, means associated with said conduits for returning the withdrawn material to said chamber, said means including at least one pipe of smaller transverse sectional area than said conduits communicating with each of the latter and with said chamber, said pipes discharging the material into said chamber at a. common level, and means for causing a gaseous medium to flow within said pipes away from said conduits, each of said pipes extending partially within and longitudinally of the associated conduit.

6. In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed, of a plurality of conduits disposed exteriorly of said chamber and communicating with the interior of said chamber at different vertical levels, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom, means associated with said conduits for returning the withdrawn material to said' chamber, and means sufiusing the material thus circulated with a gaseous medium in infinitesimally finely divided form, whereby the circulat ing material is caused to assume an approximately fluid condition.

7. In apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed,

of a plurality of conduits disposed exteriorly of said chamber and communicating with the interior of'said chamber at different vertical levels, whereby material'in different strata within said chamber may be simultaneously withdrawn therefrom, means associated with, said conduits for returning .the' withdrawn material to said.

8. In apparatus for mixing pulverulent or fine- 1y divided materials, the combination with a mixing chamber receiving the material to be mixed, of a plurality of conduits afiordifig communication between different strata of the material thus received, and means for facilitating flow of ma terial in' said conduits and preventing clogging thereof, said means including a gas-pervious support associated with eachconduit for the material therein, said support being formed of a porous substance, and means for causing a gaseous medium under presure to flow through said support andsufiuse the material in a finely divided state, whereby a condition approximating fluidity-is established in the material.

9. In an apparatus for mixing pulverulent or finely divided materials, the combination with a mixing chamber receiving the material to be mixed, of a plurality of conduits externally disposed of said chamber and communicating withthe interior of said chamber at different vertical levels, whereby material in different strata within said chamber may be simultaneously withdrawn therefrom and discharged downwardly therein, and means associated with said conduits for returning the withdrawn material to said chamber at a common level above the highest point of withdrawal.

LINA GOEBELS,

Execzgtrix of the Estate of Paul Goebels, Deceased, 

